Jim Cramer feels certain that with the Dow Jones Industrial Average at or near all-time highs, the best way to play the market is to identify stocks and sectors that haven't fully participated, but still could.

And one of those sectors may be dry bulk shipping—that is, the business of transporting commodities like coal, iron ore and grain across the ocean.

A popular way to check the health of the sector is to use the Baltic Dry Index, which tracks day rates for dry bulk shippers.

And that's exactly why Cramer think now is the time to take a look at the sector!

Wait, what?

"I believe that dry bulk shipping rates simply can't get much lower than where they are right now. When rates go much below this level, the ship owners stop taking them on voyages because they don't earn enough to cover the cost of the trip," Cramer said.

You might say things are so bad they literally can't get much worse.

In addition Cramer believes capacity will started to ebb, a problem that has been vexing the industry for years.

"2013 marks the sixth year of overcapacity in the industry, however there are signs the dry bulk shippers could be approaching an inflection point where things start to get better. Finally, they're ordering fewer and fewer new ships, and they're now scrapping old ships at record levels—that's how you get to a point where day rates can bottom and the industry can recover."

Also Cramer said some smart money billionaires are getting involved in the industry and he thinks these whales are worth watching.

"The great Wilbur Ross Jr., of WL Ross & Co, is looking to raise half a billion dollars for a new private equity fund that will buy distressed shipping and other transportation assets. Meanwhile, you have private equity outfits like Apollo Blackstone betting on a recovery in shipping."

Now, if you want to trade the trend – how should you do it?

Photographer | Collection | Getty Images

In the dry bulk space there are only three publicly traded companies left that are still large enough for Cramer to cite them on CNBC.

"Meanwhile, Diana has used the weakness in the dry bulk market to expand its fleet, buying more ships at ultra-low prices. They bought at a time when no one else could because Diana kept their powder dry with a relatively clean balance sheet," Cramer explained.

Also Cramer likes the metrics.

"Diana's currently trading at a 5.5% discount to its net asset value of $9.29, and if I'm right the value of those assets should increase dramatically over the next 18 months."

All told, Cramer said he was blessing Diana as a 'buy' because it's 'best of breed' in the space.

However it's important to note this is a higher risk investment.

"This stock is speculative," Cramer added. "If you buy, please buy in small increments and only use limit orders, not market orders."